1. Field of the Invention
The present invention relates to an injection valve and an injection valve unit of a high pressure homogenizer. Such a homogenizer is used for segmentalizing material of food, chemical goods, medical goods, various synthetic resins and the like.
2. Description of the Related Art
Conventionally, for example, there is a conventional high pressure homogenizer to segmentalize material in a suspension including fibrous cellulose by passing the suspension through a small diameter orifice at high speed under high pressure in a paper manufacturing industry or the like (for example, Japanese Patent Application Publication No. S60-19921).
However, a method using the conventional high pressure homogenizer described in Japanese Patent Application Publication No. S60-19921 is to segmentalize material with a large pressure drop by passing the suspension of the fibrous cellulose as material through a small diameter orifice formed between a valve seat and a valve element under high pressure. The valve is pressed onto the valve seat by a driving force of the cylinder having a piston, or by a pressing force of a spring for regulating an inner pressure. Therefore, it is difficult to keep a fine gap of the orifice, and a process accuracy of segmentalizing the material is not good. Further, if the orifice gap is too narrow, the material in the suspension is easily lodged in the orifice to affect the segmentalizing process. On the other hand, if the orifice gap is too wide, the segmentation accuracy is spoiled.
Further, when the suspension is viscous, the orifice having a fine gap is easily plugged so that the segmentation of the material is not carried out. Further, when the orifice is plugged, it is necessary to disassemble the high pressure homogenizer, and clean an interior of the homogenizer, and assemble again the homogenizer. Therefore, maintenance of the homogenizer is not easy.
Further, in the homogenizer using the driving force of the cylinder to press the valve onto the valve seat, it is hard to control bit by bit the cylinder to form the fine orifice gap, and such a homogenizer is not suitable for continuous running. On the other hand, in the homogenizer using the pressing force of the spring, it is hard to select a spring having a suitable pressing force, and the valve may not be fully open or closed. Therefore, the material to be processed may be leaked, or generating the high pressure may be difficult. Thus, an efficiency of the segmentation process is reduced.
Further, parts constituting the valve are easily damaged, and their mechanical lifetimes are short. Thus, the maintenance of the homogenizer is not easy and expensive.
Accordingly, an object of the present invention is to provide an injection valve and an injection valve unit of a high pressure homogenizer to allow to keep a fine gap of an orifice easily, and to prevent material from leaking. Further, even when a suspension is viscous, an orifice thereof is not plugged so that segmentation is efficiently and precisely carried out. Further, a structure thereof is simple to reduce abrasion and damage of parts, thus a mechanical lifetime is long, and it is easy to exchange parts thereof.